E. Reverchon et al., Hexane elimination from soybean oil by continuous packed tower processing with supercritical CO2, J AM OIL CH, 77(1), 2000, pp. 9-14
Hexane elimination is the most energy-consuming step-in the industrial extr
action of soybean oil. It utilizes three sets of equipment: two evaporation
stages in series followed,by a stripper at a pressure of about 0.07 bar. T
he final hexane residue in the oil is about 1000 ppm. We propose an alterna
tive to the present process for hexane elimination, based on the extraction
of the soybean oil/hexane mixture with supercritical CO2 in a continuous c
ountercurrent packed tower. In this work, we tested a soybean oil/hexane mi
xture feed containing 10% by weight of hexane. Various pressures and temper
atures of the column were tested to reduce hexane residue in the oil. The e
xtraction process was demonstrated to be very effective for hexane separati
on. Indeed, at the bottom of the column we recovered soybean oil containing
quantities of hexane as low as 20 ppm when we operated at 120 bar, 40 degr
ees C. The effect of process parameters is also discussed.